Furnace



(No Model.) a Sheets-Sheet 1.

0. MQMILLAN.

FURNACE.

No. 295,188. Patented Mar. 18,1884.

u I i (No Model.) 2 8119888 811888 2.

0. MQMILLAN.

FURNACE.

No. 285.188. Patented M814. 18, 1884.

Sra'rns UNITE CHAR-LES MOBHLLAN, CHICAGO, ILLIN 01S,

FURNACE.

SPECIFICATION forming part of Letters Patent N 0. 295,188, dated. March 18, 188%,

Application tiled October .15, 1882.

To roZZ whom it may concern;

Be it known that I, Cunnmzs )IoMILLAN, a citizen of the United States, residing in Chicage, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Furnaces, of which the following is a specification. x

My invention relates to improvements in furnaces, more particularly adapted and hereinafter described as applied to steain-boiler furnaces, in which a bridge-wall is arranged forward of the rear end of the boiler, and the space between the bridge-wall and the rear end of the furnace forms a combustion-chamber for the products of combustion of the firechamber escaping over the bridgewall.

The objects of my invention are to provide such a furnace with a reverberatory surface, the eli'ect of which shall so augment the heating capacity of the furnace as to permit a material reduction in size of fire-chamber, and a corresponding reduction in the amount of fuel necessary to be employed to attain a given degree and area of heat; to provide means for effectively removing from the reverberatory portions of the furnace the accumulation of ashes, fine particles of coal, sand, and other substances which have the effect of diminishing and destroying the reverberating and reflecting powers oi'such portions, and to make such removal without cooling or stopping the operation of the furnace; to provide means for' supplying and regulating currents of air supplied to the products of combustion; to promote perfect combustion in the combustionchamber in the rear of the bridge-wall, and for utilizing the heat of the furnace for heating said air-currents before cont-act with products of combustion; to provide a novel form of bridge-wall which shall afford the lezistpos sible resistance to flames striking against 'it from passing over it into the combustionchamber, and which wall will also cause the coal striking against it, when firing, to bank up againstand not rebound from the wall; to provide the furnace with an ash-pit of a form best adapted for effective cleaning, and 'for reverberating the heat deflected from the burning fuel on the gratebars; to provide means for dividing the air-current upon its entrance to the combustion-chamber, and for closing the (No model.)

outlets during the removal of the accumulated ashes, &-c., from the combustioirchamber and ash-pit, and correspondingly reducing the draft of the furnace, to prevent the finer par- 5 5 ticles from rising and clogging the fines of the boiler; to provide the boiler with a covering.

adapted to prevent the radiation of heat from the top of and to adjust itself to the contrac tion and expansion of the boiler, and relieve the Walls ofthe furnace from such contracting and expansive force; and, finally, in details of construction, hereinafter described and claimed; I attain these objects by devices. illustrated in the accompanying drawings, in

. which ling the cover; Fig. 7, a detailhorlzontal section, showing the concaved portion z.

Similar letters of rcferenceindicate the same parts in the several figures of the drawings.

.A A represent the end walls, and B B the side walls, of the furnace, the rear end wall and the side walls of which are respectively provided, toward their top, with a flange or horizontal extension, a and b b, from which the boiler O is suspended by means of suitable angle-irons or anchors, c, or other suitable means. The front end of the furnace is provided with the usual furnace-0pening,D, closed by a door, through which opening fuel is thrown upon the grate-bars E, which bars are of the ordinary construction, and may be supported on an angle-iron, e, and projected into the bridge-wall, as shown, or in any other usual or desirable manner. Ash-pit Fhas its sides protected by linings f f, (see Fig. 4,) 5 which linings exten d above the grate-bars, are convexed on their upper edges, and form linings for the sides of the fire-chamber, and are removable, so as to bereplaced by new linings when burnedout. The bottom of the ash-pit is removable, and inclined from the front toward the rear of the furnace, and where it .bars.

joins the bridge wall at g is concaved with the bridge-wall, so that when an ordinary scraper is introduced the ashes may be effectually and cleanly removed, which could not be if the jointure of the ash-pit with the bridgewall formed an angle.

Inclining and curving the ash-pit in the abovedescribed manner is an important feature of my invention, for the reason that it not only facilitates the removal of the ashes, but reverberates theheat deflected from the fuel and grate-bars, causing a more rapid con1- bastion of the fuel, which, together with the reverberated heat itself, materially increases the heating capacity of the furnace. The revel-berating effects of the ash-pit .may be augmented by convexing the bottom as well as inclining the bottom of the ash-pit, or by convexing said bottom without inclining it; but the construction shown is preferred, on account of its affording a better surface to draw the ashes and the scraper when removing the ashes. The ash-pit should of course be provided with a suitable door and with drafts, not here necessary to be shown. Bridge-wall G is the bridge-wall proper of the furnace, and is built and arranged in the usual manner, except so far as broadening and convexing its rear side, as hereinafter described. H is a supplemental bridge-wall conforming in height to the bridge-wall proper and having close contactthcrewith, and convexed on its upper corner next the fire-chamber, as shown at h,whi ch convexity terminates just above the grate- The extremities i of the supplemental bridge-wall, which follow the curved continuation of and rise with the curved face of the bridge-wall proper. are concaved, so as tofill in the angle otherwise formed by the juncture of the bridge-wall with the straight side walls of the fire-chamber. The supplemental bridgewall effectually protects the bridge-wall proper, and may be readily removed when burned out without disturbing the latter.

Oonvexing and concaving the supplemental bridge-wall gives it two important functionsfirst, that of its affording less-resistance to and enabling the flames striking against it or its extension i to glance over and be carried by the draft farther toward the rear of the fur; nace than if a vertical face and angular corner opposed the flame; and, second, that of affording a surface down 'which the coal thrown against the bridge-wallwill slide and bank up against the face of the wall instead of rebounding, as on a straight wall, and afterward be pushed against the bridge-wall, as is commonly required; and, furthermore, concaving and convexing the bridge-wall in this manner gives it a rcverberatory effect, which is de sirable.

I represents the combustionchamber between the bridge-wall and rear end of the fun nace, which chamber has concaved so much of its walls as is below the plane of the crown sheets of the boiler, (see Figs. 1 and 5,) or, in other Words, has a concaved bottom extending up into its side and end walls, which bottom is grooved, and the rear end wall and the bridgewalls of the furnace are perforated to receive a concaved trough, k, in which is operated a screw-conveyer,K, journaled in suitable hangers, and provided on its rear end, which projects through the furnace, with a crank, Z, for manipulating the conveyer, the outer end of the trough being closed by a suitable disk. This conveyer, when. operated, serves to draw out of the furnace the accumulation of ashes and fine particles of coalwhich escape over the bridge-wall into the combustion-chamber, and also the sand and grit given off by the walls of the combustion chamber by reason of the intense heat to which the walls are subjected. Ooncaving the walls of the combustion-chamber causes these substances to accumulate in the conveyer-trough, and not form a layer destroying the reverberatory and radiating power, as they would do if the bottom of the chamber were not inclined at a sufficient angle to cause the particles to roll into the trough. and by'the term incline it should be understood that, so far as an effective operation of the conveyer is concerned, the bottom of the combustion-chamber maybe V-sha'ped,instead of concave. Inthis connection it should be stated that the forward end of the-conveyeris closed, and that the shaft of the conveyermay'be projected and operated in the ash-pit, instead of at the rear of the furnace.

Arranged in the combustion-chamber, just above and transversely of the conveyer, are a series of bars, M, pivoted at their lower edges to the conveyer-trough by means of lugs, (see Figs. 2 and 5,) and at their upper edges by lugs to a rod, m,which, passing through, is operated from the rear end of the furnace to swing the bars, on the same principle of the slats to a shutter, to cut off or open communication between the combustionchamber and conveyer, as the case may be. These bars are hollow, and provided with openings through which air is introduced into the combustioncha-mber, as hereinafter described, the purpose of having these openings on the rear side of the bars being twofoldnamely, that of sup-. plying the air in the direction with the draft of the furnace, so as not to impede but augment the-draft, and so that the openings may not becomefilld with ashes, &c. coming over the bridge-wall during the operation of the conveyer, at which time the bars are closed upon each other, as shown in Fig. 2, to prevent lighter particles rising. These openings maybe elongated and extend thelength of the bars, or consist of a series of perforations in each bar; and in either construction the series of bars serve to divide the air-current, so that it will effectually commingle with the products of combustion escaping overthe bridgewall, the pivotal movement of the bars serving to regulate the volume of the air-current, or to cut it entirely off, as above described.

Opening upon the rear end of the furnace, and formed in the side walls thereof, are air at the rear end of the furnace, where it is closed by suitable doors, 0, through which a supply ofair may be taken, instead of taking it through the walls of the furnace and heating the air during its passage; or it may be used in connection with the heated passages, to supply an increased volume of air.

Supported by suitable angle-irons, p, resting on the boiler, is a boiler-covering, P,.preferably of fire-brick, but may be of any other suitable material, which covering has an edgesupporton flat bars q, resting upon and extending from one angle-iron c to the other, said bars, in fact, forming a basesnpport for the cover. It will be scenthat the covering, not being anchored, is free to rise and full with the boiler during the expansion and contrac-' tion of the same, but effectually prevents the radiation of heat from the same, and by its rising and falling relieves the furnacewvalls from strains, which frequently affect their stability, and is therefore an important feature of my invention. When the expansion of the boiler lifts the covering above the fiangesof the furnace, the escape of heat under the edges of the lining may be prevented by abrickwork or other suitable filling which will not interfere with the movement of the lining.

Practical experiment with my furnace has demonstrated that, with the supply of air out off from the combustion-chamber, the degree of heat is much higher than in furnaces hav ing angular combustionchambers, bridge walls, and ash-pits, which result can only be attributable toihe rererberatory effect attained by my construction, and is due, mainly, to the form of the combustion-chainber. With the supply of air out off from the combustiom chamber when firing up, the volume of smoke is not materially decreased, and the flame is dark and heavy and advances only sli htly beyond the bridge-wall; but with a supply of air througl'i the hollow bars to the combustionchamber the smoke instantly disappears, and a continuous flame darts forward to the rear end of the furnace and some two feet or more into the tines ofthe boiler, and little or no smoke appears at the stack. These results are due, partly, to supplying and the manner ofsupplyingair to the products in the comlmstiouchainher, but as a whole to the reverberatory effect of the furnace, combined with the air-suppl y, the rcrerbcratory effect of the furnace serving to raise the temperature of the products of combustion, to cause them to fully ignite when in contact with the air, the ignition of these products in the combustionchamber establishing auniform degree of heat over the entire surface of the boiler projecting into the fire andcombustion chambers. The outer ends of the airchainbers N are shown asprovided with a network of brick or iron, to divide the current; but this is not material tomyinvention, nor is the form of conveyer shown, for any other form maybe substituted, or ascraper may be employed to the same end.

By reference to Fig. 4 it will be seen that the side linings of the fire-chamber and the supplemental bridgewall are in effect a supplemental furnace, protecting and adapted to be removed from the furnace proper when burned out and be replaced with new material without disturbing the same; hence the durability of the furnace proper is very materially increased.

As will be observed, the linings and supplemental bride-wall very materially diminish the area of the grate, and with it the fire-surface of the furnace; but practical use has demonstrated that with the above-described construction less grate-surface and a correspondingly-diminished amount of fuel are required for successful operation than in furnaces constructed in the ordinary way.'

Having thus described my inventiomwhat I claim, and desire to secure by Letters Patent, is

1. The combination, in a furnace,of a bridgewall, and a combustion-chamber arranged in the rear of and extending in a plane below the top of said bridge-wall, said combustionchamber having the masonry of its longitudinal sides and bottom concaved or inclined to a uniform depth, so that the longitudinal line thereofshall be in a horizontal planemnd provided with means of access for the removal of accumulations without interrupting the operation of the furnace, substantially as described.

2. The combination, in a furnace, ofa bridgewall,and a combnstion-chamber arranged in the rear of and extending in a plane below the top of said bridge wall, said combustion-chamher having the masonry of both sides and ends and its bottom concaved or inclined to a unifo 'm depth, so that the longitudinal lines of the sides and bottom shall be in a horizontal plane, and provided with means of access for the removal of accumulations without interrupting the operation of the furnace, substantially as described.

3. 'Ihe combination, in afurnace,ofabridgewall, a combustioil-chamber in the rear thereof, and a conveyer arranged in the masonry forming the bottom of said conibustion-chamher, and adapted to removethe accumulations in said chamber, substantially as described.

t. The combination, in a furnace, of a combustion chamber arranged in the rear of the firechamber and a conveyor arranged within and in aplane below the bottom of said conibustionchamber, and adapted to remove the accumulations therein, substantially as described.

5. The combination of the combustionchamber, the bottom of which is a contiguous part of the masonry of the side walls of the boiler-setting, and is grooved to receive atoll:v

IIO

I 4 wanes mulations,and means for removing such accumulations, substantially as described.

6. The combination, with the combustionchamber, of the series of pivoted and hollow bars forming air-inlets, and means for operating said bars, substantially as described.

7. The combination, with the combustionchamber,and with the receptacle for the accumulations, of the intermediate swinging bars and means for operating the same, substantially as described.

8. The combination, in a furnace, of a combustion-chamber constructed in the masonry thereof and arranged in the rear of the firechamber, the accumulationreceptacle in the bottom of the combustion -chamber, an airchamber surrounding the receptacle, and airinlets opening into said air and combustion chambers, substantially as described.

20 9. The combination, with a furnace, of a bridge-wall the front face of which is convex and its extremities joining the sides of the furnace concaved, as at t, substantially as and for the purpose described.

10. In a steam-boiler furnace, the combinatiou,with the boiler,of a covering conforming in shapeto the upper portion of and supported by the boiler, and detached from the walls of the furnace, between which the boiler is suspended, substantially as described.

11. The combination, with the boiler, the supporting-lugs, and the side walls of the furnace, of bars supported by and connecting said lugs, and an arched covering resting on the bars, all substantially as described.

CHARLES MOMILLAN.

\Vitnesses:

J NO. G. ELLIOTT, W. W. ELLIOTT. 

